P10
Weight = mass + gravity
Mass = without gravity
Gravity = 9.8 N/kg
Terminal velocity
when a person falls
1st - accelerates due to force of gravity
2nd - drag force increases and then equals with gravity - terminal velocity
3rd - parachute increases drag force
4th - equalises again - terminal velocity
5th - lands, ground gives upward force
momentum
Mass (kg) x velocity (m/s)
vector quality
law of conservation of momentum
in a closed system, the total momentum before an event is equal to the total momentum after the event
stopping distance = thinking distance + braking distance
Factors affecting braking distance:
Tired, Drugs, Alcohol, Speed and Wet/icy roads
Forces and Elasticity
an object is elastic if it returns to it's original shape when the forces deforming it are removed
extension = length at stage - original length
Hooke's law
the extension of a spring is directly proportional to the force applied, as long as it's limit of proportionality is not exceeded
Force applied = spring constant x extension
resultant force = mass x acceleration
Newton's 2nd law
acceleration of an object is:
- proportional to resultant force
- inversely proportional to mass
the greater the resutlant force on an object, teh greater the objects acceleration
the greater the mass of an object the smaller its acceleration for a given force